The present invention generally relates to a computer keyboard, and in particular to a pushbutton structure of a computer keyboard.
Pushbuttons of keyboards comprise a movable cap and a stationary base. The cap comprises a guide post depending therefrom. The base forms a hollow silo in which the guide post is movably received for guiding the movement of the cap with respect to the base. A normally open switching circuit is formed under the base whereby the movement of the cap toward the base close the switch to generate a signal indicating the actuation of the particular pushbutton. A resilient biasing member is provided below the guide post whereby when the pushbutton is depressed to close the normal open switch, the biasing member is deformed. When the pushbutton is released, the deformed biasing member springs back and forcibly drives the pushbutton back to its original position. To ensure smooth operation of the pushbutton, the contact area between the guide post and the guide silo must be large. However, such a large contact area cause high noise. Sophisticated structures are often employed to maintain smooth operation of the pushbutton. This increases costs of manufacturing.
It is thus desirable to have a pushbutton structure of keyboard for overcoming the above-mentioned problems.
Accordingly, an object of the present invention is to provide a keyboard pushbutton which cause substantially low noise during the operation thereof.
Another object of the present invention is to provide a keyboard pushbutton having a simple structure and low costs.
To achieve the above objects, in accordance with the present invention, there is provided a keyboard pushbutton comprising a stationary base forming an upward-extending silo having a rectangular cross section having four corners. Two wedge blocks are formed on an inside surface of the silo and are opposite to each other. A movable cap forms a depending guide post movably received in the silo whereby the cap is movable, with respect to the base between a released position and a depressed position. The guide post forms two panels each defining two slits for making the panel resiliently deflectable. Each panel forms a slot defined between two ribs for movably receiving the corresponding wedge block. The ribs converge toward each other at a free end of the panel and the converging configuration of the ribs is complementary to the shape of the wedge block for effectively preventing the cap from separating from the base and slowing down the moving speed of the cap when the cap is forcibly returned back from the depressed position to the released position so as to reduce the noise caused thereby. Each wedge block forms a camming surface and the corresponding ribs form inclined lower ends cooperating with the camming surface for guiding the wedge block into the slot between the ribs. The guide post forms flanges coextensive therewith, each flange having a rounded free edge in physical engagement with the corresponding corner of the silo for guiding smooth movement of the guide post with respect to the silo.